Sanitize unfilled recv slots in flashinfer_nvlink_one_sided dispatch#9
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zyongye merged 1 commit intozyongye:nvlink_one_sided_bf16_support_upstreamfrom Apr 29, 2026
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Padded rows in the [ep_size, max_num_tokens, ...] workspace retain stale topk_ids from prior dispatch calls (the workspace is zeroed only once at init). Those stale ids cause the downstream trtllm_fp4 grouped GEMM to do phantom work for random local experts every layer, which (a) inflates expert GEMM time and (b) creates the cross-rank skew that the combine kernel then has to wait on. Setting `invalid_token_expert_id` to `num_experts` (one past the valid expert range) makes the flashinfer worker overwrite all top_k topk_ids slots of padded rows with that sentinel (moeA2ASanitizeExpertIdsKernel in moeAlltoAllKernels.cu); the trtllm grouped GEMM then sees those rows as routed to no local expert (out of [local_expert_offset, local_expert_offset + local_num_experts)) and skips them. Signed-off-by: Zijing Liu <liuzijing2014@gmail.com>
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zyongye
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) Padded rows in the [ep_size, max_num_tokens, ...] workspace retain stale topk_ids from prior dispatch calls (the workspace is zeroed only once at init). Those stale ids cause the downstream trtllm_fp4 grouped GEMM to do phantom work for random local experts every layer, which (a) inflates expert GEMM time and (b) creates the cross-rank skew that the combine kernel then has to wait on. Setting `invalid_token_expert_id` to `num_experts` (one past the valid expert range) makes the flashinfer worker overwrite all top_k topk_ids slots of padded rows with that sentinel (moeA2ASanitizeExpertIdsKernel in moeAlltoAllKernels.cu); the trtllm grouped GEMM then sees those rows as routed to no local expert (out of [local_expert_offset, local_expert_offset + local_num_experts)) and skips them. Signed-off-by: Zijing Liu <liuzijing2014@gmail.com> Signed-off-by: Yongye Zhu <zyy1102000@gmail.com>
zyongye
pushed a commit
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Apr 29, 2026
) Padded rows in the [ep_size, max_num_tokens, ...] workspace retain stale topk_ids from prior dispatch calls (the workspace is zeroed only once at init). Those stale ids cause the downstream trtllm_fp4 grouped GEMM to do phantom work for random local experts every layer, which (a) inflates expert GEMM time and (b) creates the cross-rank skew that the combine kernel then has to wait on. Setting `invalid_token_expert_id` to `num_experts` (one past the valid expert range) makes the flashinfer worker overwrite all top_k topk_ids slots of padded rows with that sentinel (moeA2ASanitizeExpertIdsKernel in moeAlltoAllKernels.cu); the trtllm grouped GEMM then sees those rows as routed to no local expert (out of [local_expert_offset, local_expert_offset + local_num_experts)) and skips them. Signed-off-by: Zijing Liu <liuzijing2014@gmail.com> Signed-off-by: Yongye Zhu <zyy1102000@gmail.com>
zyongye
pushed a commit
that referenced
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Apr 30, 2026
) Padded rows in the [ep_size, max_num_tokens, ...] workspace retain stale topk_ids from prior dispatch calls (the workspace is zeroed only once at init). Those stale ids cause the downstream trtllm_fp4 grouped GEMM to do phantom work for random local experts every layer, which (a) inflates expert GEMM time and (b) creates the cross-rank skew that the combine kernel then has to wait on. Setting `invalid_token_expert_id` to `num_experts` (one past the valid expert range) makes the flashinfer worker overwrite all top_k topk_ids slots of padded rows with that sentinel (moeA2ASanitizeExpertIdsKernel in moeAlltoAllKernels.cu); the trtllm grouped GEMM then sees those rows as routed to no local expert (out of [local_expert_offset, local_expert_offset + local_num_experts)) and skips them. Signed-off-by: Zijing Liu <liuzijing2014@gmail.com> Signed-off-by: Yongye Zhu <zyy1102000@gmail.com>
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Padded rows in the
[ep_size, max_num_tokens, ...]workspace retainstale
topk_idsfrom prior dispatch calls (the workspace is zeroedonly once at init). Those stale ids cause the downstream
trtllm_fp4grouped GEMM to do phantom work for random local experts every layer,
which (a) inflates expert GEMM time and (b) creates the cross-rank
skew that the combine kernel then has to wait on.
Setting
invalid_token_expert_idtonum_experts(one past the validexpert range) makes the flashinfer worker overwrite all
top_ktopk_idsslots of padded rows with that sentinel(
moeA2ASanitizeExpertIdsKernelinmoeAlltoAllKernels.cu); thetrtllm grouped GEMM then sees those rows as routed to no local expert
(out of
[local_expert_offset, local_expert_offset + local_num_experts))and skips them.